This type implements the IDisposable interface. When you have finished using the type, you should dispose of it either directly or indirectly. To dispose of the type directly, call its Dispose method in a try/catch block. To dispose of it indirectly, use a language construct such as using (in C#) or Using (in Visual Basic). For more information, see the "Using an Object that Implements IDisposable" section in the IDisposable interface topic. Also, note that the Dispose() method is not thread-safe. All other public and protected members of BlockingCollection<T> are thread-safe and may be used concurrently from multiple threads.

BlockingCollection<T> supports bounding and blocking. Bounding means that you can set the maximum capacity of the collection. Bounding is important in certain scenarios because it enables you to control the maximum size of the collection in memory, and it prevents the producing threads from moving too far ahead of the consuming threads.Multiple threads or tasks can add items to the collection concurrently, and if the collection reaches its specified maximum capacity, the producing threads will block until an item is removed. Multiple consumers can remove items concurrently, and if the collection becomes empty, the consuming threads will block until a producer adds an item. A producing thread can call the CompleteAdding method to indicate that no more items will be added. Consumers monitor the IsCompleted property to know when the collection is empty and no more items will be added.

Add and Take operations are typically performed in a loop. You can cancel a loop by passing in a CancellationToken object to the TryAdd or TryTake method, and then checking the value of the token's IsCancellationRequested property on each iteration. If the value is true, it is up to you to respond the cancellation request by cleaning up any resources and exiting the loop.

Do not modify the underlying collection directly. Use BlockingCollection<T> methods to add or remove elements. The BlockingCollection<T> object can become corrupted if you change the underlying collection directly.

Returns a filtered collection of elements that contains the descendant elements of every element and document in the source collection. Only elements that have a matching XName are included in the collection.